This invention relates to reel mowers, and mechanisms for changing the cutting height of reel mowers.
Conventional reel mowers provide a plurality of blades coupled together to form a generally cylindrical reel which rotates about a horizontal axis. The blades pass in close proximity to a bedknife to create a scissoring action for cutting vegetation such as grass. A frame typically houses the reel and bedknife. Wheels, rollers or skids are coupled to the frame for engaging or rolling across the ground to operatively support the reel and bedknife at a predetermined height above the ground. The height at which the grass is cut is therefore determined by the height at which the wheels, rollers or skids carry the frame, reel and bedknife above the ground. Reel mowers are typically used for mowing golf courses or other areas where a relatively low and accurate cut is desirable.
It is known to provided reel mowers with mechanisms for adjusting the height at which the grass is cut. A first type of height adjustment mechanism utilizes a plurality of vertically aligned holes formed in the cutting unit frame. The rollers are coupled to a mounting member or plate which includes an opening. The mounting plate is coupled to the frame by insertion of a pin through both the mounting plate opening and one of the holes defined by the cutting unit frame. The cutting height can be varied by inserting the pin through a different hole in the frame. The forces encountered by the rollers during operation are transferred through the mounting plate and pin mechanism and into the cutting unit frame. In order to maintain proper strength and rigidity in the frame, the holes formed by the frame must be positioned a sufficient distance from each other in order for the frame to withstand the loads from the rollers. The holes may therefore be spaced relatively far apart from each other, which results in the cutting height being adjustable in only large increments. Furthermore, differences in tolerances between the pins and holes may create gaps between the pieces of the mechanism, and may allow the mechanism to rattle or shift slightly. The rattling of the mechanism may allow the connection to wear and shift further, thereby causing an inaccurate or poor quality of cut. Also, pin connections of this type typically involve loose parts that may be lost during field adjustments.
A second type of height adjustment mechanism provides a roller coupled with a vertically extending threaded bolt. The bolt is shiftably received within an opening formed by a portion of the cutting unit frame. The bolt is shiftable up and down within the opening for adjusting the relative positions of the roller and cutting unit frame to thereby vary the cutting height. The bolt is held in vertical position by a pair of nuts which are threaded onto the bolt on either side of the opening. The nuts therefore "sandwich" the portion of the frame that defines the opening such that the cutting unit is held securely in the desired vertical position with respect to the rollers. Wrenches can be used to adjust the nuts to new positions on the threads of the bolt to thereby shift the bolt vertically within the opening for adjustment of the cutting height. The adjustment of this second type of height adjustment mechanism therefore typically involves the use of tools. The adjustment of both nuts across a large portion of each threaded bolt may consume a relatively large amount of time. Furthermore, since the each side of the cutting unit typically carries a height adjustment mechanism, the operator must use a device known as a gauge bar to determine if the entire lateral width of the cutting unit has been adjusted to the desired height. The gauge bar is also used to determine whether the cutting unit is level from front to rear, and whether the front and rear rollers are parallel. Since a gauge bar and tools must be used to properly adjust the second type of cutting unit to a new cutting height, the mowing vehicle would typically be driven back to a shop area to perform the height adjustment operation. However, since the height adjustment of this type of cutting unit is relatively time consuming, an operator will instead often chose to change to an entirely different vehicle which has a cutting unit set at a different cutting height. In other words, cutting units of this type are typically dedicated to a single cutting height, with only precise adjustments being performed. A number of vehicles each provided with a cutting unit set at a different cutting height are often employed to mow the various areas where grass is to be cut at different heights, such as on fairways and roughs of a golf course.
A third type of cutting unit provides a slotted mounting arm which is coupled with the roller. A bolt received by the slot acts to secure the mounting arm to the cutting unit frame. The cutting height is adjusted by loosening the bolt and shifting the slotted mounting arm to a new position. This type of mechanism requires the use of tools, and also the use of a gauge bar to determine whether the cutting unit is at a level and uniform cutting height from side to side and front to rear. This type of mechanism is capable of infinite adjustment through a relatively large range of different cutting heights. However, the bolts can be tightened improperly such that they become loosened during cutting operations and allow the cutting unit to slip to a different cutting height. A low quality of cut can therefore result from the use of this type of height adjustment mechanism.
A fourth type of mechanism provides a pin and hole system similar to the first type of mechanism mentioned above, however a pattern of holes are provided in both the mounting plate and the cutting unit frame. The operator can insert the pin through particular holes to set the cutting unit to the desired height. An operator must typically refer to an instructional diagram or other written directions to determine the particular holes through which the pin must be inserted to accomplish a particular cutting height. Height adjustment operations for this type of mechanism are often performed in a workshop where the operator has access to the instructional diagram. Travel time is therefore often incurred when the cutting height is adjusted. Furthermore, the pins are loose parts that could be lost if field adjustments are performed, and gaps can exist between the pin and mounting plate or frame such that rattle, wear and poor cut quality can occur.
It would therefore be desirable to provide a reel mower cutting unit height adjustment mechanism which does not involve the use of loose parts, and that is easily adjustable in the field to a variety of cutting heights with the use of only one or a small number of tools. It would also be desirable to provided a height adjustment mechanism which firmly and positively secures the cutting unit at the predetermined cutting height. It would be desirable for such a mechanism to be infinitely adjustable across an relatively large range of cutting heights, and without requiring reference to an instructional diagram. It would be desirable for such a mechanism to be adjustable for leveling the cutting unit from side to side and from front to rear.